In hydrodynamic devices, particularly torque converter devices, for heavy equipment wherein large rotating masses are involved, it has been known to have a clutch mechanism which may be operative to disengage the drive to the impeller element of the converter and to have a brake for stopping rotation of the impeller and associated elements when desired. However, control of these devices has been found to require the operator to properly sequence the apply and exhaust pressure to disengage the clutch and engage the brake or vice-versa at the proper times. If the timing is not precisely done by the operator, the result will be an inefficient type of operation wherein the brake may come on before the clutch is released, thus placing unnecessary loads on the engine; or if the brake engages too late, the elements will be allowed to spin up and cause inefficiencies and a time delay in operation of the transmission device. The problem thus recognized in the prior art and not adequately solved is to properly time the sequence of engagement and disengagement of the clutch and brake devices such that during shifting of the transmission mechanism, the rotation of the parts will be halted and the shift completed in a minimum amount of time without creating inefficiencies.